Island



(No Model.)

G. B. GOTTRELL.

OFFSET MECHANISM FOR PRINTING MACHINES.

No. 484,531. Patented Oct. 18, 1892.

THE mums versus no, mow-mum, WASHINGTON, 0.1:

UNITED STATES PATENT OFFICE.

CALVERT B. OOTTRELL, OF WESTERLY, RHODE ISLAND.

OFFSET MECHANISM FOR PRINTING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 484,531, dated October18, 1892.

Applicationfiled March 9, 1892. Serial No.424,285. (No model.)

To all whom it may concern:

Be it known that I, CALVERT B. COTTRELL, of Westerly, in the county ofWashington and State of Rhode Island, have invented a new andusefulImprovementin Offset Mechanism for Printing-Machines, of which thefollowing is a specification.

This invention is an improvement in the offset mechanism which is thesubject of my United States Letters Patent, No. 467,637, dated January26, 1892, the purpose of which mechanism is to effect the shifting of atympan on an impression-cylinder by unrolling it from one and rolling itupon another of two rollers arranged within the said cylinder, thefirst-mentioned of such rollers being called the deliveryrollers and theother the take-up roller, and the said delivery-roller having applied toit a spring by which a proper tension is applied to the tympan.According to that invention the unlocking of the delivery-roller topermit the unrolling of the clean tympan therefrom is in part controlledandthe relockingof the said rollerwhen a sufficient length of tympan hasbeen unrolled therefrom is entirely controlled by means of anon-rotating interrupted circular track concentric with the cylinder, apawl by which said roller is locked, having attached to it a slidingpiece which runs outside the said track when the pawl keeps the rollerlocked and runsinside of the said track while the pawl leaves the rollerunlocked. The interrupted circular track described in that patent ismade in one piece and the whole length of it is fixed and there is noprovision for compensating for the reduction of the diameter of the rollof the tympan on the said roller consequent upon the unwinding of thetympan therefrom.

The object of this improvement is to so compensate for this reduction asboth to equalize at all times the tension produced upon the tympan bythe aforesaid spring and to permit the greater movement of the saidroller on its axis, which is necessary to let off a given length oftympan as the diameter of the roll upon it diminishes; and to these endsthe said improvement consists in the construction of the said circulartrack of two parts and the means for its adjustment, as hereinafterdescribed and claimed.

Figure 1 represents an end-view of theimpression-cylinder of aprinting-machine and of parts attached and contiguous thereto necessaryto illustrate my invention. Fig. 2 is a top view of one end of thecylinder and of parts of the machine necessary to illustrate myinvention. Fig. 3 is a side view of one of the two parts of the circulartrack.

Similar letters of reference designate corresponding parts in all thefigures.

A designates a part of one of the journalboxes for theimpression-cylinder O.

b is the tympan.

c is the delivery-roller, d the take-up roller, and e f thefeed-rollers.

D is the spur-gear concentric with the cylinder, attached by brackets gto the journalbox A, and gearing with a pinion G on the feed-roller ffor the purpose of producing the shifting of the tympan by the rotationof the cylinder at such times as may be desirable. This gear D, havingno rotary motion and only rising and falling with the cylinder, will behereinafter referred to as the stationary gear.

J J designate the locking-pawl for locking the delivery-roller(represented asa lever) fulcrumed on the stud j, secured to one head ofthe cylinder 0, one arm of the said lever being furnished with teeth jjto engage with the teeth of the ratchet-Wheel 0 which is fitted looselyto the shaft or journal of the delivery-roller c and connected with thesaid delivery-roller by the coiled spring 0 one end of which is securedto the said shaft or journal and the other end to the ratchet-wheel, thesaid spring when the ratchet-wheel is locked having a tendency to turnthe delivery-roller in a direction to wind up and produce tension on thetympan. The other arm J of the said lever has connected with it a rod 7'which passes through the guide f secured in the cylinder-head, betweenwhich guide and the nut or collar j on the said rod there is coiled onthe said rod the spring f, which serves to throw the teeth j of the pawlinto engagement with the ratchet-wheel 0 when permitted to do so.

'1 T designate the non-rotatinginterrupted circular track forcontrolling the operation of the locking-pawl J J, and j is the slidingpiece attached to the said pawl for running on the outside or inside ofthe said circular track, as required, according as the deliveryroller islocked or unlocked. In Fig. 1 the said sliding piece is represented asrunning on the inside of the track and about to pass by the end 10 ofthe interruption 1O 11 of the said track and permit the teeth of thepawl to engage with the ratchet-wheel and lock the roller.

The parts thus far referred to, so far as they have been described, arethe same as the corresponding parts in my hereinbefore-mentioned LettersPatent.

I will now proceed to describe the improvement in detail. Thenon-rotating interrupted circular track T T is made of two pieces T andT. These are both represented as fitted to the interior of the opencenter of the stationary gear D, which thus constitutes asupport for thesaid track concentric with the cylinder. The piece T (represented asconstituting the greater portion of the length of the said track) isfirmly secured to the said interior of the gear by screws 8 s, and thepiece T is secured to the said interior by screws 15 t in such manner asto permit the said piece T to be moved forward and backward from andtoward the piece T, or, in other Words, more or less forward in thedirection of the rotation of the cylinder 0, which is indicated by thearrow in Fig. 1, the provision for this movement being made by slots u uin the piece T, the screws t 15 passing through the said slots andscrewing into the gear D. The adjustable portion of the said track isprovided with a laterally-projecting lug '0, through which is inserted ascrew w, which works in a nut as, which is rigidly attached to thesupport of the trackthat is to say, in this example to the stationarygear D. The screw w is represented as confined longitudinally in the lug1), but free to turn therein, so that by turning it it operates in thenut to move the movable part T of the track from and toward the part T,and so to adjust the point 10 of the track more or less forward in thedirection of the revolution of the cylinder, so that the sliding piecewill drop off the point 10 earlier or later in the rotation of thecylinder.

The operation is as follows: When a new tympan is put in the cylinderand the diameter of the roll on the delivery-roller is the largest, theadjustable part or member T of the non-rotating track is brought closeup to the part or member T; but from time to time as the tympan isunwound from the said roller and the diameter of the roll thereondiminishes, and consequently a greater movement of the said roller isnecessary to let off or deliver a given length of tympan and a lessleverage is produced by the pull of the tympan on the spring, thepressman or attendant turns the screw in a direction to set the member Tof the track and the end 10 thereof farther forward. The etfect of thisis that the sliding piece j of the locking-pawl escapes later and laterfrom the said end 10 and out from the interruption or opening of thetrack and leaves the delivery-roller longer unlocked and permits it tobe turned the greater distance necessary. The roller itself does not,however, stop as the pawl first engages with and stops the ratchet-wheel0 but continues moving and winding up the spring 0 by which the tensionof the tympan is controlled, and as the pawl escapes later and laterfrom the end 10 of the track it winds up the spring less and less, sothat its tension is proportionate to the leverage of the tympan on theroller. The adjustment of the part T of the track by the screw-w maybeperformed while the press is in motion, and the accuracy of theadjustment may be facilitated by providing a scale on the gear D todetermine the position of the point 10, according to the size of theroll.

What I claim as my invention, and desire to secure by Letters Patent,is-

1. The combination, with the impressioncylinder, a tympan-deliveryroller therein, and a pawl attached to the'said cylinder for locking thesaid roller, of a non-rotating interrupted circular track made in twoparts, one of which is adjustable relatively to the other in thedirection of the rotation of the cylinder for holding the said pawl outof engagement with the cylinder during a greater or less portion of therotation of the latter, sub- ?tanfiially as and for the purpose hereinset ort 2. The combination, with the impressioncylinder, atympan-delivery roller in said cylinder, and a pawl attached to saidcylinder for locking said roller, of an interrupted circular track forsaid pawl made in two parts, a support for said track upon which one ofthe said parts is secured firmly and the other is adjustable, and ascrew and nut, one of which is attached to said support and the other tosaid movable part of said track for adj usting the latter in thedirection of the rotation of the cylinder, substantially as and for thepurpose herein set forth.

CALVERT B. COTTRELL. Witnesses:

WM. E. DAVIES, CARL MOLLER.

